We are engaged in the investigation of light-harvesting system from photosynthetic cyanobacteria and red algae. The principal thrust of the research is determination of the three-dimensional structures of the principal components of this light-harvesting system, the phycobiliproteins. The techniques employed in this study are single crystal x-ray diffraction and electron microscopy. The primary goals of our work are two-fold; we expect to gain an understanding of light harvesting from a knowledge of the arrangement of chromophores in the phycobiliproteins and ultimately in the cell, and we hope that study of the arrangement of phycobiliproteins into organelles, the phycobilisomes, will assist us in understanding other sorts of biological assembly.